Machine for grinding material

ABSTRACT

This disclosure relates to a machine for grinding material in a powder or liquid phase, the machine including a housing, grinding means within the housing, means for mounting the grinding means for rotation relative to the housing, the grinding means being defined by a pair of frusto-conical surfaces converging toward each other, the housing including like frusto-conical surfaces to define with the pair of frusto-conical surfaces a pair of frustoconical gaps through which the material which is adapted to be ground is passed, means for feeding the material to be ground into one of the gaps at a narrower end of one of the frustoconical surfaces, and means for removing ground material from the other of said gaps at a wider end of the other of the frustoconical surfaces. The gap most adjacent the feed means is in converging relationship away therefrom whereas the gap most adjacent the removing means is in diverging relationship therefrom, and means are provided for axially relatively adjusting the grinding surfaces relative to each other and to the housing.

ilited States Patent n91 Zucker MACHINE FOR GRINDING MATERIAL Friedrich J. Zucirer, Norf, Germany Supraton Auer & Zuclter OIIG, Allerheiligen. Germany Mar. 21, 1974 inventor:

Assignee:

Filed:

Appl. No.:

[30] Foreign Application Priority Data References Cited UNITED STATES PATENTS 3/1888 Wimmer 24l/l46 l2/l946 Fisher et al. 24l/259.l 3/1948 Zwoyer 24i/l46 Primary Examiner--Roy Lake Assistant Examincr--E. F. Desmond Attorney, Agent, or Firm--Diiler. Brown, Ramik & Wight Oct. 28,1975

[57] ABSTRACT This disclosure relates to a machine for grinding material in a powder or liquid phase. the machine including a housing, grinding means within the housing, means for mounting the grinding means for rotation relative to the housing. the grinding means being defined by a pair of frusto-conical surfaces converging toward each other, the housing including like frusto conical surfaces to define with the pair of lrusto-conical surfaces a pair of frusto-conical gaps through which the material which is adapted to be ground is passed, means for feeding the material to be: ground into one of the gaps at a narrower end of one of the frusto-conical surfaces, and means for removing ground material from the other of said gaps at a wider end of the other of the frusto-conical surfaces.

6 Claims, 1 Drawing Figure U.S. Patent 0m. 28, 1975 MACHINE FOR GRINDING MATERIAL The present invention relates to a machine for finely and ultra-finely grinding material in its powder or liquid phase wherein grinding gaps are formed between two grinding elements movable relative to one another. the grinding elements being in the form of grinding means defined by a pair of frusto-conical surfaces converging toward each other disposed within a housing which also includes substantially similar frusto-conical surfaces to define therebetween a pair of frusto-conical gaps between which the material which in to be ground is fed.

it is well-known that products suspended or dispersed in liquids can be continuously reduced or ground by roll stands. for example. three-roll and similar multiroll stands. However. since the grinding elements in such conventional roll stands are only in linear contact the efficiency of the grinding operation is disproportionately low relative to the financial outlay or cost involved. Moreover. abrasion is high and this presentsa serious deterrent particularly due to heating and attendant wear of grinding surfaces.

Conventional ball mills are also known in which the material is forced therethrough by balls which are kept in constant motion by means of stirrers and the like. in ball mill or bead mills of this type. the result of the grinding operation in regard to the eventual quality of the ground product is not independent of the pressure under which the material is fed or delivered. As a result there are limits to the fineness to which the material can be ground.

it is also common to employ impeller grinding machines which include a rotor and stator whose opposite surfaces have rings carrying projections or the like which are alternately arranged adjacent one another in .a radial direction. The material which is to be reduced passes between the rotor and stator where it is reduced in size either by friction, by impact. by shear action, by cavitation. or the like during relative rotation. and any material which might be soluble in a dispersion medium is dissolved. Obviously. the profile surfaces of the stator and/or rotor are size reducing tools with the degree of size reduction and hence the maximum grain size of the end product being varied both through the interval or gaps between the rotor and stator and through the configuration thereof. Needless to say. the fineness of the grind is limited by the lowest possible tolerance permissible between the rotating components (rotor vs. stator). and the finenessof the grinding gap cannot be reached below such tolerance limit.

in keeping with the foregoing. a major object of this invention is to provide a novel grinding machine for achieving finely and ultrafinely ground material in either a powder orliquid phase in which the conventional grinding gap is totally independent of conventional variables and can be adjusted and remain constant. as might be required. during a grinding operation. The grinding machine according to the present invention is distinguished from the prior art by the fact that the grinding elements are in the fomi of two oppositely directed frustoconical surfaces arranged in a common housing which are non-rotatable relative to each other. but relative to the housing. and the frusto-conical surfaces define with the housing a pair of tapering annular gaps between which the ground medium passes between an inlet and an outlet during a grinding operation.

The foregoing arrangement is free from bearings of the conventional type which require rotating grinding elements and the grinding gap also remains constant at a required setting during a grinding operation and is independent of the pressure under which the material is fed therethrough. The grinding elements are automatically concentrically adjusted relative to any countergrinding. and in this manner there is a certainty of size of the eventually ground material.

in cases where the material is to be ground. is introduced under a predetermined pressure the grinding gap or gaps which are of a predetermined size are automatically adjusted in relation to the coaxial position of the frusto-conical grinding surfaces and the countergrinding surfaces of the housing. By such arrangement the delivery of ground material is kept constant.

in further keeping with this invention the provision of the opposite frusto-conical surfaces or cones permit axial forces which might be generated by one cone to be cancelled by the other due to the opposite arrangement thereof. The material being ground in and of itself acts as a form of bearing or lubricant for the rotating grinding surfaces or elements-s0 that there is no need for additional mechanical bearings for the relatively rotatable grinding elements.

During the grinding operation an equilibrium is thereby established between two oppositely directed elements in regard to the grinding gap therebetween and under these circumstances it is possible to obtain grinding gaps which can be kept very much narrower than in conventional grinding machines. Whereas the fineness of grinding has been heretofore, limited to about my, it is possible with the machine of the present invention to grind materials much more finely. namely. to a fineness of up to about 5-1 my. By virtue of the present machine. not only is it possible to obtain products ground to the aforementioned fineness. but it is also possible to insure that the material flowing from the grinding machine is ground to the required fineness throughout. As a result there is no longer any need to later pass the ground material through a filter in order to separate coarser grains from finer grains. as is now conventionally done. Thus, the grinding machine of the present invention insures an output of a homogeneous grain size which can be accurately adjusted in advance by machine adjustment.

The present invention is moreover desirable because the machine is small, uncomplicated in structure and employs a fairly minimal power requirement.

in further accordance with this invention the frustoconical grinding surfaces or cones are arranged in such a way that they widen toward axially outermost ends defining gaps which widen axially toward each other and toward the narrower ends of the cones. Preferably. at least one cone can be axially adjusted and locked so that a grinding gap of a predetennined size can be maintained constant to achieve desired output product size.

The frusto-conical surfaces or cones are stationary relative to each other except for the fact that they are axially adjustable to achieve the change in gap dimension heretofore noted. The peripheral surfaces of the cones and the inner surfaces of theassociat'ed housing are preferably completely smooth so that fine and altrafine grinding can be safely achieved with the delivery of the ground material being substantially free from friction. 1

The grinding machine of the present invention is quite suitable for any pumpable product or slurry be it in liquid or powder form, and in the case of a powder the only requirement is that it should flow freely under pressure so that the behavior of the same corresponds generally to the behavior of hydraulic substances.

With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claimed subject matter, and the several views illustrated in the accompanying drawing.

IN THE DRAWING The single FlGURE of drawing is a diagrammatic longitudinal sectional view taken through the grinding machine according to this invention, and illustrates a pair of frusto-conical cones whose like surfaces cooperate with like surfaces of a housing to grind material passing through frusto-conical gaps defined therebetween.

The novel grinding machine of this invention is generally designated by the reference numeral 1 and includes as grinding elements a pair of frustoconical cones 3, 4 having exterior frusto-conical surfaces (unnumbered) which oppose similar frusto-conical surfaces Sa, Sb of a housing 5 to define therebetween a pair of annular gaps 6, 7 which are also frusto-conical except for a cylindrical portion 50 therebetween. it is to be particularly noted that the cones 3, 4 are arranged with their narrower ends (unnumbered) disposed immediately adjacent each other and the wider ends disposed remote from each other. Likewise, the surfaces 5a, 512 have their narrower or smaller diameters adjacent each other and the wider diameters remote from each other.

The cones 3 and 4 are of a tubular configuration and are slidably mounted upon a rigid shaft 8 which projects from the machine 1 at at least one end thereof, and is mounted for rotation in a rigid mounting 9 which includes a cover 10 and threaded bolts 11 which function as a bracket. The cone 4 is fixedly connected to the shaft 8 by screws 12 and a conventional key 13. A closure 14 is countersunk to receive the screws 12 and is attached thereby to the shaft 8.

The grinding element or frusto-conical cone 3 is preferably arranged for axial adjustment relative to the shaft 8. in this regard the shaft 8 is provided with a thread 15 upon which is screwed or threaded an adjusting ring 16 having in its periphery a radial bore 17 as well as a scale or indicating surface 18. A sleeve 19 is disposed between the cone 3 and the adjusting ring 16. The sleeve 19 is fixed to the cone 3 and may also be fixed to the adjusting ring 16. As will be noted hereinafter it is sufficient for axial pressure to be applied to the cone 3 to the adjusting ring 16 because the grinding-gap 6 is automatically adjusted in an opposite direction by the material passing through it. The cone 3 is prevented from rotating relative to the shaft 8 by means of a key 20 which is axially shorter than the associated slot (unnumbered) to provide relative adjustment axially of the cone 3 relative to the shaft 8. The ring 16 may, of course, be rotated to raise or lower the cone 3 and thereby adjust the dimensions of the gap 6 between the cone 3 and the associated surface 5a of the housing 5. The graduations 18 permit rapid adjustment or an indication thereof, and any setting achieved thereby can be maintained through the use of locking screws associated with the bores 17.

The material which is to be ground is delivered through the shaft 8 by means of a bore 21 which leads to an annular intermediate zone 22 between the cones 3 and 4 in the area of the surface 5c by means of a transverse bore 23. The material is discharged from the bottom of the machine 1 through a bore 24 of the shaft 8 which communicates with an intermediate zone 25 through a radial bore 27 and an annular groove 28.

The housing 5 is closed by a plate 29 by means of conventional bolts 30 and a seal 3! is provided to maintain a fluid type arrangement between the sleeve 19 and the housing 5. A corresponding closure plate 32 is united to the housing by fasteners 33 and seals (unnumbered) are provided as necessary. The housing 5 is surrounded by a heating or cooling jacket 34 which defines an annular space 35 into which is connected an inlet pipe 36 and an outlet pipe 37 for the introduction and removal, respectively, of a heating or cooling medium. The medium is introduced through a stub shaft 39 which is fixedly connected to the housing 5 and is surrounded by a sleeve 40 which includes ports 41, 42

in communication with the pipes 36, 37, respectively. Appropriate seals 43, 44 may be provided to prevent leakage of the circulated material.

The stub shaft 39 is connected through a clutch 45 to a drive motor 46 which enables the housing 5 to rotate relative to the frusto-cones 3, 4. Moreover, as indicated by the unnumbered double headed arrows in the drawing, the housing may be raised or lowered vertically and thus may be axially displaced relative to the cones 3, 4.

The material which is to be ground is drawn from a reservoir 48 by a gear pump or the like 47 and delivered to the infeed pipe 21 through a conduit 49. The material after being ground is withdrawn from machine 1 through the discharge pipe 24, a conduit 50, and is deposited in a collecting vessel 51.

in order to carry out the grinding operation the cone 3 which is axially displaceable on the shaft 8 is first adjusted by means of the adjusting ring 16 so that the very narrow annular gaps $2, 53 between the cones 3, 4 and the housing surfaces 5a, 5b are adjusted to a required size. Providing the surfaces of the cones and the corresponding conical inner surfaces of the housing are suitably designed, it is possible to adjust the annular gaps S2, 53 at the wider ends of the cones 3, 4, respectively, as narrow as approximately 1 my by means of the ring 16. The taper of the grinding gap 6, 7 is best when at, for example, my or even larger at either inlet end.

When the grinding machine is inoperative the housing 5 rests firmly on one of the two oppositely directed cones and is thus non-rotatable. When brought into operation the material is delivered by the pump 47 through the conduits 49, 21 under a predetermined pressure such that the material is forced through the grinding gaps under the effect of the pressure during the rotation of the cones 3, 4 relatively to the housing 5. The material is thus forced into the annular space 22 and enters the gaps 6, 7. inasmuch as the housing 5 is rotated by means of the motor 46 there is an automatic adjustment in the position thereof relative to the cones 3, 4 and thus achieving a relative adjustment of the gap 6, 7 such that the same gap width exists in each. Thus the grinding material and its pressurization automatically determines the predetermined grinding gap which will remain constant under the action and reaction effect of the oppositely directed cones 3, 4 and the setting, of course, of the ring 16. Accordingly. the fineness of grinding remains strictly constant.

The grinding machine may also be designed in such way that one cone is elastically mounted axially and is under the effect of an elastic counter-force. such as a spring. An axial bearing may also be provided for any such cone which is elastically displaceable. in this case it is possible to obtain hydraulic adaption relative to the grinding gap selected and in special cases it is also possible to employ but a single cone in which case the cone or housing is rotatably mounted. However, a relative axial disposition or movement between such single cone and housing is not required.

The machine heretofore described is designed preferably for ultrafinely grinding substances in the plastic field, for example, starting materials for man made fibers, organic or inorganic pigments, coating compositions, and medium in the food line such as starting materials of the kind used in the production of chocolate products or even for the production of powders in the costmetics field and the like. The grinding machine can also be used for homogenizing various kinds of substances consisting of different liquid, solid and/or a combination phase. Furthermore, the machine can be used as a heat exchanger for thermal processes.

While preferred forms and arrangements of parts have been shown in illustrating the invention, it is to be clearly understood that various changes in detail and arrangement of parts may be made without departing from the spirit and scope of this disclosure.

I claim:

I. A machine for grinding material comprising a housing, said housing including a pair of frusto-conical surfaces converging toward each other, grinding means within said housing, means for relatively rotating said housing and grinding means, means mounting said housing and grinding means for free axial floating movement relative to each other along the axis of relative rotation of said housing and grinding means, said grinding means being defined by a pair of generally smooth frusto-conical surfaces devoid of projections. said last-mentioned frusto-conical surfaces converge toward each other and each defines with an associated one of said housing frusto-conical surfaces a frustoconical gap. said frusto-conical gaps converge in directions away from each other, means at the narrower end of each frusto-conical gap for conducting ground matcrlal outwardly of said housing, and means for delivering material to be ground contiguous the wider end of each frusto-conleal gap.

2. The machine as defined in claim 1 wherein said rotating means imparts rotation to said housing.

3. The machine defined in claim 1 including means for axially relatively adjusting said housing and grinding means.

4. The machine as defined in claim 1 including means for axially relatively adjusting said housing and grinding means, said adjusting means includes a collar mounted for axial adjustment relative to a shaft, and said grinding means being carried by said shaft whereby selective axial displacement of said collar relative to said shaft adjusts the axial position of said grinding means relative to said housing.

5. The machine as defined in claim 2 including means for axially relatively adjusting said housing and grinding means.

6. The machine as defined in claim 2 including means for axially relatively adjusting said housing and grinding means, said adjusting means includes a collar mounted for axial adjustment relative to a shaft, and said grinding means being carried by said shaft whereby selective axial displacement of said collar relative to said shaft adjusts the axial position of said grinding means relative to said housing.

I i l l l 

1. A machine for grinding material comprising a housing, said housing including a pair of frusto-conical surfaces converging toward each other, grinding means within said housing, means for relatively rotating said housing and grinding means, means mounting said housing and grinding means for free axial floating movement relative to each other along the axis of relative rotation of said housing and grinding means, said grinding means being defined by a pair of generally smooth frusto-conical surfaces devoid of projections, said last-mentioned frustoconical surfaces converge toward each other and each defines with an associated one of said housing frusto-conical surfaces a frusto-conical gap, said frusto-conical gaps converge in directions away from each other, means at the narrower end of each frusto-conical gap for conducting ground material outwardly of said housing, and means for delivering material to be ground contiguous the wider end of each frusto-conical gap.
 2. The machine as defined in claim 1 wherein said rotating means imparts rotation to said housing.
 3. The machine as defined in claim 1 including means for axially relatively adjusting said housing and grinding means.
 4. The machine as defined in claim 1 including means for axially relatively adjusting said housing and grinding means, said adjusting means includes a collar mounted for axial adjustment relative to a shaft, and said grinding means being carried by said shaft whereby selective axial displacement of said collar relative to said shaft adjusts the axial position of said grinding means relative to said housing.
 5. The machine as defined in claim 2 including means for axially relatively adjusting said housing and grinding means.
 6. The machine as defined in claim 2 including means for axially relatively adjusting said housing and grinding means, said adjusting means includes a collar mounted for axial adjustment relative to a shaft, and said grinding means being carried by said shaft whereby selective axial displacement of said collar relative to said shaft adjusts the axial position of said grinding means relative to said housing. 